BY Alec Marshak & Kyle Harding Making an ellipse BY Alec Marshak & Kyle Harding

Supplies Two pushpins A piece of computer paper A big piece of cardboard A 20cm long piece of string that is tied together to form a loop Lastly you need a pencil

Steps # 1-3 First fold the paper in half like a hot dog then open it and place it on the cardboard Now draw two dots that are two centimeters apart in the middle of the paper Now label the left focus F1 and the right focus F2 (The Sun)

Steps #4-7 Place the pushpins into the two dots. Make sure to have pushed the pushpins all the way into the cardboard Now you will put the string around the pushpins and insert your pencil inside the string loop Use it by drawing a circle while puling outward on the string with your pencil (make sure the string stays on the pins)

Congratulations Steps 7-8 Take out the pushpins Now draw a straight line through the middle of the ellipse connecting the foci to the outside of the ellipse and label it the major axis Lastly, hand the perfect ellipse to your Earth Science teacher and hope for the best Congratulations

Finding the Eccentricity When finding the eccentricity of an ellipse, you use the equation e=d/l . e=eccentricity, d=distance between foci, and l=length of major axis. So the steps are… Measure the distance between the foci.(cm) Measure the length of the major axis.(cm) Divide the distance between the foci by the length of the major axis and the answer is the eccentricity.(cm to the nearest thousandth)

Our Ellipse So using the steps from the last slide, we will figure out our ellipse’s eccentricity. The d=2 cm and the l= 10.8 cm.Next we divide 2cm by 10.8cm which equals .185.So our ellipse has an eccentricity of .185. Now that we know our ellipse’s eccentricity we can compare it to another planet’s eccentricity. Compared to Mercury’s eccentricity our planet’s eccentricity is less eccentric. If our ellipse was a planet’s orbit, and it was compared to Mercury’s orbit our planet’s orbit would be less than and more circular.